I did a little bit of investigation and found that you can, in fact, use discs with the Joliet 3 filesystem specification in Mac OS X 10.3. These discs can come from Windows users who burn dsics with DirectCD for Windows. Although Mac OS X will automatically mount discs burned with the Joliet Level 1 or Level 2 extensions to the ISO-9660 filesystem, I've had several users complain about not being able to mount "PC CDs." As it turns out, those discs were using the Joliet Level 3 extensions to ISO-9660. Here's how to make them work:

Insert the disc, and open Terminal and Disk Utility.

In Disk Utility: Determine the device identifier of the disc you inserted. Click the CD session (or volume) in the devices list in Disk Utility and click the Info button. Look for "Disk Identifier," and note the value. For example, on my iBook, it's disk1s0 (d-i-s-k-number one-letter "s"-number zero) for the fist volume on a CD in my internal Combo drive.

In Terminal, do the following:

Create a mount point with this command, replacing mount_point with a name of your choice: mkdir /Volumes/mount_point

Tell cd9660.util to force-mount the volume on the CD to the mount point. Replace disk_identifier with the disk identifier from Disk Utility (step two above), and replace mount_point with the name of the mount point you just created: /System/Library/Filesystems/cd9660.fs/cd9660.util -M disk_identifier /Volumes/mount_point

Tell applications that a new volume is available by typing disktool -r.

Work with the disc as usual, ejecting it using the Finder when you're done. I've found that file sizes may not be reported correctly for files on the CD, but the files can be copied from the CD if you have trouble.

Yes, the method you describe allows you to get the system to mount these disks. Unfortunately in some cases, the system still can't contend with the content correctly. If I look at the mounted disk with the Finder, things look basically OK, but as you state the file sizes are not correctly reported. If I try to copy a directory from the CD to the desktop, I get the following error "You cannot copy 'datar' to the destination because its name is the same as the name of an item on the destination, except for the case of some characters". From the terminal the directory looks like this.

I guess that there is support for level 3 as the CDs burnt by Finder supports or has level 3 incorporated into the hybrid CD that is created. The problem could be the strange conflict because of MS attempts to reconcile MS-DOS and Win 95 systems in the past:
http://docs.info.apple.com/article.html?artnum=20752

But all this still do not explain why we need to manually mount a level 3 CD or DirectCD created CD using this hint or the AppleScript that follows this hint. The script works wonderfully fine!

Great hint! It works perfectly for me on the two Joliet 3 CD I have tried it with.

I wrote a quick Applescript that automates this process somewhat. I am not the greatest scripter so if you see flaws in the script's logic or improvements to be made please let me know so I can learn.

Here's the script:

try
tell application "Finder" to set finderDisks to name of disks
set currentDisks to do shell script "disktool -l"
set AppleScript's text item delimiters to return
set currentDisks to every text item of currentDisks
set unmountedVolLine to ""
repeat with currentLine from 1 to the count of items in currentDisks
if item currentLine of currentDisks does not contain "volName = ''" then
repeat with i from 1 to the count of items in finderDisks
if item currentLine of currentDisks contains "volName = '" & item i of finderDisks & "'" then
exit repeat
else
if i = the (count of items in finderDisks) then
set unmountedVolLine to item currentLine of currentDisks
exit repeat
end if
end if
end repeat
end if
if unmountedVolLine is not equal to "" then
set AppleScript's text item delimiters to "'"
set diskIdentifier to text item 2 of unmountedVolLine
do shell script "mkdir /Volumes/temppccd; /System/Library/Filesystems/cd9660.fs/cd9660.util -M " & diskIdentifier & " /Volumes/temppccd; disktool -r"
exit repeat
end if
end repeat
if unmountedVolLine is equal to "" then display dialog "There are no unmounted disks." buttons "OK" default button "OK"
set AppleScript's text item delimiters to ""
on error error_msg number error_num
set AppleScript's text item delimiters to ""
display dialog "Error " & error_num & ": " & error_msg buttons "OK" default button "OK"
end try

I tried the script (thanks!) to mount Joliet CDs created by a cardiac ultrasound unit, that stores files in DICOM format.
It mounts fine, but the files come out with some corrruption, as no DICOM viewer (e.g. Escape, or OsiriX) can open them. My current solution is to use Thomas Tempelmann's Joliet file system extension, which runs under OS9 - but, unfortunately, can't be used in Classic mode.
It would be nice if a solution that is fully OSX-compatible comes about.
Still, thanks for the efforts.
Xen

GREAT! Finally I have all of my digital photo CDs I made with my PC laptop on my G5... it worked, thanks! However each of the original TIF files (Minolta Dimage7) will not open now. Somehow this method has corrupted the files and none of my photo/image/graphic software will recognise them. The smaller thumbnails of the same files (on the same CDs) open OK. Weird.
Those that I import direct from the camera I have no problem with.

Alas, I found the same problem today, in 10.3.4. I used the script [thanks!], but found that some PSD files would not open -- they are corrupted somehow. So, I added something to the script:
display dialog "Warning: this script attempts to mount \"Joliet 3\" CDs that a Windows user made, but, probably, not all files will copy safely. Until OSX is patched, you must use a Windows PC to ensure file safety with Joliet 3 CDs." buttons "OK" default button "OK"

i'm trying to get this to work but keep running into this issue- any ideas on how to work around this?
[code]
Silver:~ eric$ mkdir /Volumes/pcdisc
mkdir: /Volumes/pcdisc: File exists
Silver:~ eric$ /System/Library/Filesystems/cd9660.fs/cd9660.util -M disk2s0 /Volumes/pcdisc
mount_cd9660: Input/output error
[/code]

Here's a word from the author of the "Joliet Volume Access" and "Adaptec UDF Volume Access", which can both read such DirectCD discs on Mac OS 7-9.

It is quite clear that the ISO 9660 driver in OS X is not able to read fragmented files, as they may only appear in ISO 9660 Level 3 discs (but not in Level 1 and 2).

Now, if you use the above method to mount such a disc on your Mac, it only means that you can access unfragmented files. But those that are fragmented (that's the ones that appear with multiple identical names in a listing in Terminal) can not be read completely as either the OS X driver would have to know how to concatenate them into one single complete file, or would allow us to read all the pieces and put them together ourselves. Neither works, however.

Hence, if some of you report that they could read all their files, then you were just lucky that none of them were fragmented on the disk (or you haven't even noticed yet that you have some incomplete files now).

Whether you have fragmented files on a disk or not depends on the software that wrote it, and how. I'd suspect that those Sony cameras who write pictures to CD-R are able to write the picture files in one piece (unfragmented) to the disc, so you'll be able to read those pictures just fine with the methods described here. But if you've used DirectCD on Windows, it's more likely that large files that you copied to the CD-R are fragmented, as that's how DCD works when it writes large chunks of data - it can't write them contiguously, or so I believe.

I hope this clears up the effects people have seen here.

Basically, if you have a Level 3 disc that you can only access with the methods described here, better make sure that when you copy the files off of the CD, that they're really all complete. If you have incomplete files or other read problems, you need to use a Windows system or Mac OS 9 with my Joliet driver (www.tempel.org/joliet/) to read them properly.

Wow this thread is amazing iv been baffled by this issue for a while - as my old cd's work on 10.6 but not on mountain lion.
I guess mountain lion dropped support for joliet leve3?
can anyone help me update the script to work on 10.8, i replaced disktool with diskutil but it still gets stuck at this line? set diskIdentifier to text item 2 of unmountedVolLine
any help would be greatly appreciated.
I have tested it in terminal and it works doing the following
mkdir /Volumes/tempCD
sudo /System/Library/Filesystems/cd9660.fs/Contents/Resources/cd9660.util -M disk1s1 /Volumes/tempCD
sudo /System/Library/Filesystems/cd9660.fs/Contents/Resources/cd9660.util -u disk1s1 /Volumes/tempCD

i didn't know the diskutil command for disktool -r which i guess allows you to eject the mounted partition in the finder?
so had to use the -u command to unmount it.
also i like the idea of the script to automatically detect the correct unmounted volume. would save a lot of time on the 30+ disks i need to convert / re burn.

any help would be greatly appreciated.

try
tell application "Finder" to set finderDisks to name of disks
set currentDisks to do shell script "diskutil list"
set AppleScript's text item delimiters to return
set currentDisks to every text item of currentDisks
set unmountedVolLine to ""
repeat with currentLine from 1 to the count of items in currentDisks
if item currentLine of currentDisks does not contain "volName = ''" then
repeat with i from 1 to the count of items in finderDisks
if item currentLine of currentDisks contains "volName = '" & item i of finderDisks & "'" then
exit repeat
else
if i = the (count of items in finderDisks) then
set unmountedVolLine to item currentLine of currentDisks
exit repeat
end if
end if
end repeat
end if
if unmountedVolLine is not equal to "" then
set AppleScript's text item delimiters to "'"
set diskIdentifier to text item 2 of unmountedVolLine
do shell script "sudo /System/Library/Filesystems/cd9660.fs/Contents/Resources/cd9660.util -M " & diskIdentifier & " /Volumes/temppccd" with administrator privileges
exit repeat
end if
end repeat
if unmountedVolLine is equal to "" then display dialog "There are no unmounted disks." buttons "OK" default button "OK"
set AppleScript's text item delimiters to ""
on error error_msg number error_num
set AppleScript's text item delimiters to ""
display dialog "Error " & error_num & ": " & error_msg buttons "OK" default button "OK"
end try